City Trees

March - April 2012

City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!

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years ago for their attractive ornamental qualities. The fast growth of these plants and the abundant red ber- ries are seen as positive qualities for a landscape plant, but unfortunately these are some of the same qualities that make them hypercompetitive and highly invasive. I Bush honeysuckle shrubs planted for their beauty are botanical bullies that create unsightly tangles in nearly every bit of unmanaged greenspace throughout greater Columbus, greater Cincinnati, points west in between those two cities, and undoubtedly in other urban areas throughout the state. Observant residents can see that most parks, river corridors, and rights-of-way here in Franklin County are now teeming with non-native inva- sive honeysuckle shrubs, especially amur honeysuckle (Lonicera maackii). One thing is for certain: emerging invasive plants in urban forests will have to be able to hold their own against bush honeysuckle and other invasive plants like tree-of-heaven (Ailanthus altissima) that already have a strong foothold in the landscape. A few popular land- scape plants are starting to become more and more noticeable (to me) in parks, along waterways, bike trails, and roadways, as well as in public and private forestland throughout Ohio. Perhaps they are reaching the end of the "lag phase" that occurs after introduction and before exponential spread and naturalization. Will they be able to stand up to competition from honeysuckle and other established invasives? Time will tell. In my opinion, privet is the likely leader among those emerging invasive plants. Like bush honeysuckle, Japanese and European privet as well as several other Ligustrum species were introduced here as ornamen- tals. Escaped privet can grow almost anywhere that bush honeysuckle grows but it appears to do really well in moist riparian areas. It is creeping into city parks, cemeteries, and other urban green spaces. I have seen some private woodlands where privet is just as widespread and abundant as bush honeysuckle. So the potential for invasiveness is there, but will privet find an open niche in the urban forest? Some other popular ornamental plants like Japanese bar- berry (Berberis thunbergii) and burning bush (Euonymus alatus) have also been observed in our region's natural areas. For the most part, they are not yet causing the damage that honeysuckle does but they have dem- onstrated their ability to reproduce and colonize new habitat. The good news is that awareness of invasive plants seems to be increasing and people are getting involved to address the issue. I have worked with a number of volunteer groups to control invasive plants in public www.urban-forestry.com n central Ohio, where I live, there are many very large bush honeysuckle shrubs (Lonicera sp.) growing in home landscapes where they were planted parks. The most ambitious volunteers are often the youngest, like Boy Scouts and high school students. Hopefully awareness of invasive plants will continue to grow as these young people mature into adults who will remain active in their communities. Another bit of good news is that some home garden- ers are beginning to recognize the beauty of many of our native plants and the benefits they provide. Being an avid native plant gardener myself, I was happy to see that one of the big box home improvement stores is now carrying a number of native perennial plants and they are marketed as such. This would seem to indicate that there is an increasing demand for native plants and an awareness of the potential perils of plant- ing non-natives in our landscape. —Annemarie Smith, Invasive Species Forester, Ohio DNR Division of Forestry and their adverse impacts in New England and Long Island, New York. Professionals, conservation organiza- tions, cooperative extension and university staff, and state and federal representatives have worked hard to educate the public on invasive species. F This has led to research, regulations, on-the-ground management, and accompanying ecological restoration. It has also lead to passage of state and county bans on the sale, transport, distribution, and propagation of specified invasive plants—starting with a ban enacted by the State of Connecticut in 2004. The Commonwealth of Massachusetts followed in 2006 with a statute nego- tiated with some forward-thinking nursery owners in the lead. Now, an increasing number of conservation commissions here on Cape Cod and elsewhere in the Commonwealth require some measure of invasive spe- cies management and replacement with native plants as part of a permitted property improvement. In 2007 both Nassau and Suffolk Counties on Long Island passed a similar ban on selected invasive species; you can see a comprehensive "Do Not Sell" list of banned plants within their excellent publication: http://ccesuffolk. org/assets/galleries/Agriculture/Commercial-Nursery- and-Landscape-Management/Website-FAQ-on-Invasives- Brochure-2012.pdf The history of invasive species in the Northeast starts with arrival of European colonists in the 17th century. The New England Wildflower Society estimates that about 60% of the invasive exotics we struggle with were originally brought here as ornamental plants. This includes our "kudzu of the North," oriental bittersweet (Celastrus orbiculatus), as well as Japanese honeysuckle 23 irst, the good news: for at least two decades there has been a steadily increasing understanding of and concern for invasive exotics

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